The invention relates to a high-voltage electric circuit-breaker, such as a compressed-gas puffer circuit-breaker including an interrupting chamber with at least one moving contact inside the chamber, the moving contact being actuated by means of a spring-loaded mechanical control mechanism so as to open or close the circuit-breaker, the control mechanism including at least one first spring exerting a force tending to move the moving contact to open the circuit-breaker, and a second spring exerting a force tending to move the moving contact to close the circuit-breaker while loading the first spring, and in which circuit-breaker an additional spring is provided for exerting an additional force that is added to the force exerted by the first spring at the beginning of circuit-breaker opening.
Such a circuit-breaker is already known from U.S. Pat. No. 4,228,333. In the control device of that circuit-breaker, the additional spring contributes to increasing the speed at which the moving contact moves at the beginning of circuit-breaker opening. That additional spring ceases to exert the additional force once the moving contact has moved over a certain distance in its opening stroke, so as not to impede slowing down the moving contact at the end of circuit-breaker opening. But that configuration of the additional spring requires more energy to be delivered to the second spring in order to close the circuit-breaker, because it must load not only the first spring, but also the additional spring.
An object of the invention is to propose a particular configuration for a circuit-breaker as defined above, which configuration does not need additional energy to load the additional spring during circuit-breaker closure.
Another object of the invention is to provide a particular configuration for such a circuit-breaker that further makes it possible to recover and to store a portion of the kinetic energy from the moving contact at the end of opening or of closure, so as to use it at the beginning respectively of a subsequent closure operation or of a subsequent opening operation.
To this end, the invention provides an electric circuit-breaker including an interrupting chamber with at least one moving contact inside the chamber, the moving contact being actuated by means of a spring-loaded mechanical control mechanism so as to open or close the circuit-breaker, the control mechanism including at least one first spring exerting a force tending to move the moving contact to open the circuit-breaker, and a second spring exerting a force tending to move the moving contact to close the circuit-breaker while loading the first spring, and in which circuit-breaker an additional spring is provided for exerting an additional force that is added to the force exerted by the first spring at the beginning of circuit-breaker opening, wherein the additional spring is mounted so that, before the end of circuit-breaker opening, the resultant of the force exerted by the additional spring for moving the moving contact is reversed so as to oppose the movement of the moving contact.
Thus, at the end of circuit-breaker opening, the additional spring is loaded by the movement of the moving contact and it is thus not necessary to use a portion of the energy from the second spring of the control mechanism to re-load the additional spring during circuit-breaker closure. Since the moving contact moves essentially due to its own kinetic energy at the end of opening, the additional spring can serve to recover and store a portion of this kinetic energy which is otherwise consumed conventionally in a damper device.
In a particular embodiment, the control mechanism includes a rotary shaft movably coupled to the moving contact and rotated alternately by the first spring and by the second spring. The additional spring is coupled to the rotary shaft via a lever fixed to the rotary shaft and occupying two end angular positions corresponding to the positions of the moving contact when the circuit-breaker is respectively open or closed. The force exerted by the additional spring on the lever is oriented so that its rotational component changes direction when the lever goes through an intermediate angular position as it goes from one end angular position towards the other end angular position. Thus, the lever operates as a pendulum with the additional spring. At the beginning of opening, the resultant of the force exerted by the additional spring is added to the force exerted by the first spring, which tends to accelerate the speed at which the moving contact moves. At the beginning of circuit-breaker closure, the resultant of the force exerted by the additional spring is added to the force exerted by the second spring, so that it is possible to reduce the energy that is required for the control mechanism to engage the circuit-breaker.
In a particular embodiment of the circuit-breaker of the invention, the additional spring is coupled to the lever via a pulley, which makes it possible to dispose the additional spring in the vicinity of the interrupting chamber of the circuit-breaker so as to make the circuit-breaker more compact. This additional spring is preferably always loaded in compression.
In a particular embodiment of the circuit-breaker of the invention, the lever is a triangular-shaped lever or bell-crank that has one vertex that coincides with the rotary shaft and two other vertices coupled respectively to the moving contact and to the additional spring.